REPEATED BIOMASS REMOVAL AFFECTS SOYBEAN RESOURCE UTILIZATION AND YIELD

Authors: Singer, Jeremy; Meek, David

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2004
Publication Date: 9/15/2004
Citation: Singer, J.W., Meek, D.W. 2004. Repeated biomass removal affects soybean resource utilization and yield. Agronomy Journal. P. 1382-1390.

Interpretive Summary: Soybean producers in many regions of the U.S. are confronted with significant yield losses because of crop damage from white-tailed deer, but little information exists that quantifies the extent of yield losses. Our objectives were to quantify soybean resource utilization and yield responses to variety, row spacing, and simulated repeated biomass removal. Field research was conducted in 2000 and 2001 near Pittstown, NJ. Biomass removal during early vegetative and vegetative/reproductive growth extended the soil wetness duration index in 2000 and 2001. Biomass removal during early vegetative growth delayed pod maturity up to seven days compared to the control, but biomass removal during reproductive growth hastened pod maturity by as much as three days. All biomass removal treatments lowered soybean seed yield compared to the control except the mid vegetative/early reproductive treatment for one variety in 2000 in the 20 cm row spacing and the same treatment in 2001, averaged across variety and row spacing. The greatest seed yield reductions occurred (up to 86%) when biomass was removed repeatedly during vegetative and reproductive growth. Reductions in pod number and seed weight contributed more to lower seed yield than changes in seed number per pod. Soybean producers can reference these data to approximate yield losses from repeated deer depredation. And these data indicate that varieties within the same maturity group and row spacings ranging from 20 to 76 cm do not consistently affect yield when soybean is subjected to repeated biomass removal.

Technical Abstract: Soybean [Glycine max (L.) Merr.] producers in many regions of the U.S. are confronted with significant yield losses because of crop damage from white-tailed deer (Odocoileus virginianus). Our objectives were to quantify soybean resource utilization and yield responses to variety, row spacing, and simulated repeated biomass removal. Field research was conducted in 2000 and 2001 on a Quakertown silt loam soil near Pittstown, NJ. Biomass removal during early vegetative and vegetative/reproductive growth extended the soil wetness duration index on average by 1.5 and 2.9 days compared to the control from the 0 to 30 and 30 to 60 cm soil depths in 2000 and 5.1 and 2.1 days in 2001. Biomass removal during early vegetative growth delayed pod maturity up to 7 days compared to the control, but biomass removal during reproductive growth hastened pod maturity by as much as 3 days. All biomass removal treatments lowered soybean seed yield compared to the control except the mid vegetative/early reproductive treatment for 93B53 in 2000 in the 20 cm row spacing (598 vs. 541 g m-2) and the same treatment in 2001 (700 and 731 g m-2), averaged across variety and row spacing. The greatest seed yield reductions occurred (up to 86%) when biomass was removed repeatedly during vegetative and reproductive growth. Reductions in pod number and seed weight contributed more to lower seed yield than changes in seed number per pod. Soybean producers can reference these data to approximate yield losses from repeated deer depredation to assist with management practice selection.